The method required you to have an Apple developer account to get a hold of the 4.2 beta 3 IPSW (although the firmware could be pirated, the iPhone Dev Team is strictly against piracy).

Sunday, via Twitter @MuscleNerd of the iPhone Dev Team announced that the untethered jailbreak Monte has been successfully ported back to the 4.1 kernel (SHSH blobs) for iOS 4.2.1.This means that you will now be able to use your saved iOS 4.1 SHSH blobs to get an untethered jailbreak on iOS 4.2.1…

Additionally, the Dev Team is now working on porting it forward to iOS 4.3 beta so that we may all enjoy an untethered jailbreak on iOS 4.3 as well!

There wasn’t any release date announced for the redsn0w 0.9.7 beta that would make use of your 4.1 SHSH blobs, but the Dev Team’s track record speaks for itself. I’m sure we can expect it soon.